Flotation of metallic oxides iii

ABSTRACT

A process for the flotation of metallic oxides in which a dispersed pulp is conditioned in a number of stages to achieve differential flocculation of the metallic oxides and dispersion of the gangue materials prior to flotation.

United States it 1 emos RUUGHER TAILS ROUG CONCENTRATE TAILING POND I TO3107 CLEANERi I FILTERINfi @1 1 ALTERNATELY BIRECTLY T6 FILTENINfiSOLIDS TO CONDITIONING $73965 TC 501955 16 SOLIDS [72] inventor DavidWeston 3,138,550 6/1964 Woolery 209/5 Suite 500 129 Adelaide Street,Toronto, 3,229,917 1/1966 Miller 241/16 Ontario, Canada 3,292,78012/1966 Frommer 209/166 X [21} Appl. No. 633,241 2,407,651 9/1946Clemmer 209/166 [22'] Filed Apr. 24, 1967 2,439,200 4/1948 Booth 209/166[45] Patented June 29,1971 2,470,150 5/1949 DeVaney 209/166Continuation-impart 01 application Ser. No. 2,570,120 10/ 1951 Handley209/166 X 550,922, May 18, 1966, now abandoned 2,669,355 2/1954Archibald 209/166 and a continuation-in-part ofSer. No. 2,769,541 1H1956 Perry 209/166 564.033. July 1], 1966. This application 2,944,6667/1960 Bunge 209/5 Apr. 24, 1961, Ser. No. 633,241 3,094,484 6/1963 RizoPatron... 209/166 1 1,974,885 9/1934 Wiston 209/166 [54] FLOTATION 0FMETALLIC OXIDES 11111 7 FOREIGN ENTS [52] ide/{E6571ma i/2% Gaudin,FLOTATION, McGraw-Hill, 1957 pg. 123 {5U c "M2,: 17/00, gg HANDBOOK OFMINERAL DRESSING, 1947,

B03d 1/02 [50] Field 01 Search 209/166, Primary Examiner-Frank W. Lutter167, 5; 241/20, 24, 16 Assistant Examiner-Robert l-lalper Attorney-Smart& Biggar [56] References Cited UNITED STATES PATENTS 1,585,756 5/1926Borcherdt 209/5 ABWIIRACT: A process for the flotation of metallicoxides in 2,551,893 5/1951 Morton 241/20 which a dispersed pulp isconditioned in a number of stages to 2,666,588 l/1954 Schack 241/20achieve differential flocculation of the metallic oxides and 2.861.68711/1958 Lord 209/167 dispersion ofthe gangue materials prior toflotation.

GRINDING 62 Q m 9E CONDITIONING 6 50 smee 11;

CONDITIONING STAGE 1;

h z CONDITIONING 6' STAGE 6 e:

CONDITIONING 5 3 JA 3 171615 54 FLOTAIION RUN OF MINE ORE PRIMARY IOCRUSHER PRODUCT WET AUTOGENOUS MILL I 2 CLOSED CIRCUIT OR ROD MILL -BALLMIL CIRCUIT.

PRODUCT CLASSIFIER I5 I6 OVERSIZE UNDERSIZE :2 FLOCCULATING AGENTTHICKENER I 7 i i OVERFLOW TO /-I8 I9 PLANT WATER UNDERFLOW FIG!INVENTOR DAVID WESTON ATTORNEYS PATENTEU JUN29 |9?| ""EITHER OPEN 0RCLOSED cIRcuIT TOTA L PRODUCT BALL MILL

OSED CIRCUIT PRODUCT 26A-L CLASSIFIER OVERSIZE RUN OF MINE 0m:

PRIMARY CRUSHER I PRODUCT DRY AUTOGEN OUS EITHER OPEN OR CLOSED CIRCUITBALL MILL OPEN cIRcuIT UNDERSIZE FLOCCULATING /2 AGENT THIcKENER FIGZOVE RF LOW PLANT WATER SUPPLY UNDERFLOW INVENTOR DAVID WESTON ATTORNEYSPATENIEI] JUN29 I97! SHEEI 3 BF 4 RUN OF MINE oRE PRIMARY 4O cRusHER IPRODUCT F I G. 4 DRY AUTOGENOUS MILL EITHER OPEN OR ,/42 CLOSED cIRcuITCLASSIFIER 4/43 45 44 I I ovERsIzE FINES 5o BY wEIsHT 50 BY WEIGHT WATERl BALL MILL TOTAL PRODUCT AGITATOR PRODUCT PULP 6O%LSOLIDS wETcLAssIFIER- 48 50 FINES OVERSIZE 50% BY WEIGHT I 20% soLIos 49 IINVENTOR DAVID WESTON ATTORNEYS PATENTEUJUNZ ISII 3.589.622

SHEET u [If 4 GRINDING CONDITIONING STAGE CONDITIONING STAGECONDITIONING STAGE REAGENT ADDITIDN's AS REQUIRED CONDITIONING 5 3 STAGEFIG. 5

4 FLOTATION I ROUGHER TAILS gggfifig fi TAILINGS POND TO 3m? CLEANERS II w I I FINAL COMBINED CONCENTRATE CLEANER TAILS I I RETURN TO BA-LLMILL TO THICKENING AND CLASSIFIER MAY REDUCE FILTERING 0R ALTERNATELYSDI-IDS To CONDITIONING INVENTOR DAVID WESTON BY ATTORNEYS IFLOTA'IION01F METALLIC OXIDES III This application is a continuating-in-part of myprior applications Ser. No. 550,922, filed May 18, 1966 now abandonedand 564,033 filed July 11, 1966.

This invention relates to a process for the flotation of metallic oxidesand metallic oxides with water of crystallization in chemicalcombination.

Although much has been written in the technical literature concerningthe flotation of this class of materials and a vast amount of money hasbeen spent on research for many years particularly in respect to ironores of this class, these materials remain for the most part refractoryto economic flotation.

I have now found a process by which these materials may be readily andefi'ectively concentrated by flotation without the need for anydesliming prior to flotation.

My invention does not involve the employment of new or unusual reagentsnor does it depend upon the use of special apparatus nor of techniquesbeyond the skill of those currently versed in the flotation art. Myinvention on the other hand, consists in the employment of a particularsequence of carefully controlled process steps which I have found to benecessary to obtain a controlled differential flotation of minerals ofthe above class. I have found that metallic oxides tend to flocculatewith the gangue materials in the ore, this tendency being aggravated bythe high degreeof sliming which normally results from the highproportion of natural slimes in the ores and the fine grind necessary toachieve mineral liberation. Where the mineral and gangue materials areflocculated together prior to flotation it becomes impossible to obtainany useful degree of concentration by floating the thus flocculatedmaterial. It is the solution to this problem which enables my newprocess to be effective.

GENERAL DESCRIPTION OF THE INVENTION According to my invention thecomminuted ore in a pulp is initially caused to become dispersed to asufficient degree that minimum flocculation is present. The achieving ofsuch dispersion (which I herein call effective dispersion) in someinstances with particular ores requires careful control of pH,conditioning time and addition of reagent. In other cases it is readilyachieved without the addition of reagent over a substantial range of pHsand conditioning times. When effective dispersion has been achieved abeaker sample of the pulp will, while standing, usually give a visualindication in that the minerals settle leaving a supernatant liquid inwhich the gangue materials can be seen to be suspended. The effectivelydispersed pulp is then conditioned with a collecting agent for themineral using a quantity of reagent and a conditioning time determinedexperimentally for optimum results and the pH is adjusted to a value atwhich the mineral constituents of the pulp will flocculate in thepresence of the collecting agent used. This value is usually on the acidside and is generally quite critical for any particular mineral orcombination of minerals present in the ore. The pulp is conditioned atthis new pH for a period sufficient to initiate flocculation of themineral constituent, which flocculation may again be observed visuallyin a beaker sample. The pH of the pulp is then raised to within theoptimum range of pHs for flotation of the mineral constituents concernedand the pulp is further conditioned for a predetermined period to bringabout conditions of dispersion which will keep the gangue materialseffectively dispersed with the obtaining of final heavy flocculation ofthe metallic oxide and hydrated metallic oxide constituents of the ore.The pulp is then subjected to flotation to produce a concentrate of themetallic oxides and hydrated metallic oxides.

The collecting agent used does not appear to be critical to the successof the process. Fatty-acid-type collectors have been found to beeffective as have combinations of fatty acid and petroleum sulfonatefatty acid and fuel oil as well as combinations of fatty acid, petroleumsulfonate and fuel oil. Where fuel oil has been used in conjunction withthe collectors a surprisingly small amount of l to 3 pounds per tonofore is required for optimum results. This is in contradistinction toreported processes employing fuel oil in conjunction with fatty acidwhere from a minimum of 7 pounds to upwards of 200 pounds per ton havebeen reported as having been necessary.

Where a dispersing agent is necessary I prefer to use sodium silicatewhich is the most readily available and economical of those commonlyemployed in flotation, however, conventional dispersants such as sodiumhydroxide, lignen sulfonate and silicon tetrachloride can be used, asthe general effectiveness of the process does not appear to depend uponthe selection of a particular dispersing agent but rather upon theachieving of the correct degree of dispersion.

Where the initial dispersion stage is conducted in an alkaline circuitthe use of an electrolyte under some conditions of operation has shownappreciable improvements in metallurgical results. The selection of theelectrolyte does not appear important so long as it does not produceions detrimental to flotation of the particular minerals present. Sodiumfluoride, sodium sulfate and sodium chloride have all been successfullyused although sodium chloride in some cases produces a froth conditionwhich is less easily controlled.

The flotation circuit used may be of conventional design and willnormally include an appropriate number of cleaning stages either withoutor with appropriate conditioning between some or each of the stages. Inmost cases the conditioning between cleaning stages will be for thepurpose of producing conditions of additional dispersion employingcontrolled amounts of dispersing agent for this purpose. I have foundsurprisingly however, that in the later stages of cleaning some of thecarbonates which tend to float in the process with the metallic oxidesare effectively depressed by lowering the pH of the pulp to the acidside of the scale and conditioning with controlled amounts of sodiumfluoride.

DESCRIPTION OF THE MANNER IN WHICH THE INVENTION MAY BE CARRIED OUT Themanner in which the various steps of my new process may be carried outcan vary to a substantial extent and will depend in most instances uponthe nature of the ore being treated and the equipment employed in theparticular plant concerned for the preparation of the pulp. In plantswhere a wet grinding circuit precedes the flotation circuit it is, withsome ores, possible to employ the grinding circuit to produce theeffective dispersion necessary in the first step of the process. Thismay be accomplished by adding dispersing agent directly to the grindingcircuit. With some ores which readily achieve effective dispersion thenature of the ore and of the water used may render the use of adispersing agent unnecessary. In a batch-type laboratory mill it ispossible on certain ores to add the dispersing agent and/or thecollecting agent in a grinding circuit so that the mill product may bepassed substantially directly to the initial flocculation stage of theprocess. What appears most important is that the pulp be in effectivelydispersed condition when the collecting agent is added to it, regardlessof whether this condition results from a natural condition of the oreand plant conditions so that the minerals which are released duringgrinding inherently have this characteristic or whether it is necessaryto bring about this condition with a dispersing agent as alreadydescribed.

For the flocculation stage in some cases where the nature of the ore andwater used are such that a neutral or slightly acid pulp result from thedispersion stage of the process the addition of a fatty acid collectormay alone be sufficient to lower the pH to within the optimum range forinitial flocculation. In most cases however, the pH will be adjustedwith an acid reagent. Any acid reagent which does not introduceundesirable ions into the pulp is suitable. I prefer sulfuric acidbecause of its relative cheapness and availability. Where an alkalineagent is required similar considerations apply. I prefer to use sodiumsilicate as this acts both as a dispersing agent and an alkaline agent,but sodium hydroxide and other chemicals conventionally used may be usedin place of sodium silicate or together with it.

The initial pH to which the pulp is lowered for the initial flocculationstage depends upon the particular mineral or minerals in the ore and maybe neutral or near neutral or in some cases as low as pH 5.0.

In raising the pH for purposes of carrying out the final preflotationconditioning stage an alkaline agent may be added. However, in manycases the ore itself contains acidconsuming constituents and in somecases these may be sufficient to return the pulp to near neutral orslightly alkaline. I have found that the preferable range for optimumflotation is from approximately 7.2 to approximately 8.5 although incertain cases a slightly lower or slightly higher pH can producesatisfactory results. With some ores it is most important in the finalpreflotation conditioning stage to control closely quantities ofdispersing agent and the time of conditioning, the optimum quantity andtime being different for each ore and requiring predetermination byexperiment. With other ores the quantity of dispersing agent and thetime of conditioning are more flexible.

Importance ofconditioning Times:

As will be apparent, in the process of the invention great importanceattaches to the order and concentration of reagent addition at thebeginning or during each of the various cycles. The time period of eachcycle is of prime importance and may vary within limited periodsdependent on the reagent balance used, the condition of the pulp eitherduring or following comminution, and the density of the pulp in thevarious cycles.

Considering it as a four-stage conditioning cycle, the grinding stagemay in suitable cases be regarded as the first cycle. During thegrinding stage we may have the following conditions:

Example (a) of Four-Stage Conditioning Cycle:

Sufficient dispersion of the pulp may result due to the characteristicsof both the solution used and the soluble salts in the ore, and the pHof the pulp both during and after comminution. In such a case, noreagent addition is necessary to the grinding stage. The second stageconsists of the addition of the collecting, and if required, modifyingagent such as fuel oil wherein the pH may be either on the alkaline oracid side. Al ternately, it maybe necessary to adjust the pH, eitheralkaline or acid, with reagents that do not affect the flotabilitycharacteristics of the metallic oxides, or alternately, the finaldepression effect on the waste host rock materials. The acid reagentnormally used is sulfuric acid, and the alkaline reagent, sodiumhydroxide. These reagents are comparatively cheap and normally readilyavailable. This second stage of conditioning in the four-cycle circuithas been illustrated as between a minimum of 4 minutes to a maximum ofl6 minutes with 8 minutes being generally optimum. The pH of this secondstage is in the range ofa maximum of 8.9 to a minimum pH of 6.5. Theoptimum is usually in the range of 6.8 to 8.2.

The third-stage conditioning is the lowering of the pH, normally withthe use of sulfuric acid. Where the initial pH is towards the high endof the alkaline range, the pH for this third stage need only be loweredto close to neutral. Where the first stage is near the middle of therange the pH may be lowered to as low as 5.0. Where the pH is loweredtowards the lower end of the acid range, normally acid-consumingconstituents in the ore will bring the pH back towards neutral by theend ofthe conditioning cycle. The time period of this cycle is normallyquite critical and is in the range ofa minimum of 8 minutes to a maximumof 16 minutes with the optimum being approximately 12 minutes.

The fourth cycle consists in raising the pH either to slightly acid,i.e., a pH of approximately 6.7-6.95, or to as high as a pH of 8.5. Thismay be accomplished by the use of an alkaline agent such as sodiumhydroxide, or alternately, with an alkaline-dispersing agent such assodium silicate, or alternately, with the combined use of an alkalineagent such as sodium hydroxide and sodium silicate, although depressingagents other than sodium silicate may be used, such as silicontetrachloride, lignen sulfonate or the like. Where sodium silicate isused comparatively large concentrations may be required. The amount ofsodium silicate necessary may be as high as 15 pounds per ton. The timecycle required for this stage is critical for the type or ore, thedensity of the pulp and the combination of reagents used in the previousthree cycles. It may vary from a minimum of4 minutes to a maximum of 24minutes. The normal optimum time is l020 minutes. Example (b) ofFour-Stage Conditioning Cycle:

On some ores, to obtain optimum results it may be necessary to add adispersing agent either to the grinding circuit, or alternately,following the grinding circuit. Where it is necessary to add thedispersing agent, in each case the other three cycles remain the same.Where the dispersing agent is added to the grinding circuit, oralternately, following the grinding circuit, the amount used is within acritical range and must be closely controlled. Where it is addedfollowing the grinding stage, the conditioning time differs fordifferent conditions of operation such as pulp density and the pH, theminimum time required for optimum results has been found to be 3 minuteswith a maximum of 15 minutes. The optimum time has been found to beapproximately 10 minutes. Where it is added following the grinding stagewe can consider, with the grinding stage forming the first cycle, thatwe now have five cycles instead of four. Where the dispersing agent isadded to the grinding circuit it is normally unnecessary to follow witha conditioning cycle prior to the addition of the collector.

Example (c) of Four-Stage Conditioning Cycle:

In some cases the collector and/or modifying agent may be added to thegrinding circuit with or without the dispersing agent. The optimumcondition is normally with the addition of both dispersing agent andcollector, rather than the collector alone. Where the collecting and/ormodifying agent is added to the grinding or No. l cycle, normally ashort conditioning period of up to 8 minutes must still be required inthe second cycle, although this cycle with some ores and operatingconditions may be eliminated and the pH adjusted to what would normallybe the third stage of conditioning. This time of conditioning isnormally a maximum of 16 minutes.

Example (d) of Four-Stage Conditioning Cycle:

There is an exceptional condition, wherein in the grinding circuit,optimum conditions of dispersal are achieved, and the surfaces of theminerals remain in readily activated condition. Considering thecomminution stage as Cycle 1 and no reagent added to the grindingcircuit other than the dissolved reagents that are returned in the millsolution water, the second conditioning stage can be eliminated as aseparate stage. In such as case the collector and/or modifying agentsare added following the grinding circuit and the pH adjusted to theoptimum either before or after the addition of the collecting and/ormodifying agent. The conditioning time under such conditions will varybetween 4 minutes and 20 minutes with the optimum being normally in therange of 8 to 16 minutes. The final cycle of dispersion may be carriedout at the end pH of the pulp, or alternately, at a raised pH as notedin the previous examples. Again, for each condition of pH, density ofthe pulp and characteristics of the ore, the concentration of thedispersing agent and the time-cycle are critical. The minimum time isnormally 4 minutes and the maximum 25 minutes with the optimum being inthe range of 10-15 minutes. The prolonged period of conditioning isnormally used where the dispersing agent is added over various periodsof time in the time-cycle period. The shorter time of the conditioningcycle may be used where the reagent is all added at the beginning of thecycle or, say, in two stages. In the latter case the optimum period isnormally in the range of l0 15 minutes.

EXAMPLES OF LABORATORY TESTS EMPLOYING THE PROCESS OF THE INVENTION Myinvention is illustrated by the following examples of direct flotationofiron ores.

EXAMPLEI In this example a number of tests were made on an iron ore inwhich approximately percent of the iron was present in the form ofmagnetite and approximately 30 percent in the form of specular hematite.The ore also contained varying minor amounts of iron silicates. Samplesof this ore were prepared in a laboratory rod mill and then subject toconditioning and flotation in accordance with the process of theinvention in a Fagergren flotation cell. The following two tests, number513 and 5 l7,give a comparative illustration of the importance ofobtaining effective dispersion during the initial stage of the process.In these tests the sodium silicate was added to the grinding stagefollowed by addition of the same amount of fatty acid and fuel oil ineach case with conditioning. Sulfuric acid was then used to bring the pHdown to ap proximately 6.2 and after a period of conditioning the pulpdue to acid-consuming constituents therein had returned to a pH ofapproximately 6.8. The flotation was carried out in this slightly acidcircuit.

in test 513, 2.77 pounds per ton of sodium silicate was added to thegrinding circuit and the rougher tailing produced was 9.7 percent byweight analyzing 5.21 percent iron. in test 517, where 3.89 pounds perton of sodium silicate was added the rough tailing was percent by weightanalyzing only 4.97 percent iron. illustrating a greater rejection ofwaste host rock and also better activation of the iron minerals as shownby the lower railings iron analysis. In test 518 a further increase inthe sodium silicate to 4.4 pounds per ton only slightly increased thetailings rejection to 16.8 percent by weight but the iron flotation wasseriously affected with the tailings analysis in creasing to 7.93percent iron.

The foregoing tests indicate that in the case ofthe are tested thequantity of dispersing agent is a critical factor in obtaining effectivedispersion ofthc pulp permitting effective tailings rejection insubsequent flotation.

EXAMPLE ii A sample of ore from the same area as that used in example Icontaining 68 percent of the iron as specular hematite, 30 percent asmagnetite and 3. percent iron silicate was brought to a state ofeffective dispersion by grinding for 18 minutes in a laboratory rod millat a pulp density of 60 percent solids in the presence of 3.9 pounds perton of sodium silicate as dispersing agent and 0.275 pounds per ton orsodium fluoride was added as an electrolyte. The pulp was thenconditioned for ti minutes with 1.04 pounds per ton of fatty acid. 1.53pounds per ton of petroleum sulfouatc and 2.16 pounds per ton of fueloil as collecting agent. The pi i was then lowered to slightly on theacid side by the addition of 2.14 pounds per ton of sulfuric acid andthe pulp subjected to 1.6

minutes of conditioning to initiate flocculation of tho mineralconstituents. The phi of the pulp was then raised to within the optimumrange for flotation by the addition of 2.77 pounds per ton of sodiumsilicate with a further conditioning time of 6 minutes.

The thus conditioned pulp was then subjected to flotation employing fivestages of cleaning with 10 minutes of conditioning after the third stagewith the addition of 0.42 poun s per ton of sodium fluoride and 6.9pounds per ton of sulfuri acid to drop the carbonates. The resultingconcentrate was 44.8 percent of the hands by weight. contain d 63.53percent iron representing a recovery of 81.57 percent. The acid sold hisiron in the tallings analysed 1.29 percent iron.

EXAMPLE iii Another sample of the some one as that used in example iiwas subjected to the some conditioning procedure followed by flotationwith the difference that instead of conditioning with sodium fluorideand sulfuric acid after the third cleaner the pulp was conditioned for 5minutes after the second cleaner with 0.42 pounds per ton of sodiumfluoride and 6.9 pounds per ton of sulfuric acid and after the thirdcleaner the pulp was conditioned for 5 minutes with 0.28 pounds per tonof sodium fluoride and an additional 6.9 pounds per ton of sulfuricacid. The concentrate produced was 41.8 percent by weigh of the headsample and contained 64.92 percent iron with a recovery of 75.96 percentof the total iron.

Comparing the metallurgical results in this example with those inexample ll it will be apparent that the more drastic use of sodiumfluoride dipping more deeply into the acid side has resulted in animprovement of the concentrate grade by depressing more carbonates andcombined particles. The head sample of the ore analyzed 1.40 percent CaOand 1.76 percent MgO with siliceous material being predominant in thegangue. The concentrate analyzed 0.75 percent CaO, 0.79 percent lVigOand 3.93 percent SiO Thus the use of sodium fluoride at a low pii hasnot only effectively depressed the silica as would be expected but hasin addition surprisingly depressed the calcium and magnesium carbonates.it is also evident that the iron minerals once floated can withstandthis low pH ofinitially about 4.0 to 4.5 without their floatabiiitybeing adversely affected.

The reagent balance employed in this example approached the optimum forthe particular ore concerned. Both the quantity of dispersing agent andthe time of conditioning in the final conditioning stage proved to bequite critical. The use of lesser quantities of sodium silicate thanthat indicated produced less efficient tailingsrejection in the roughertailing while the use of higher quantities resulted in depression of theiron minerals and thus a higher loss of values in the rougherconcentrate. Shorter conditioning times tended to produce lower gradeand recovery in the concentrate whereas longer conditioning times had anadverse effect upon tailings rejection and tended to depress the ironminerals producing a bad effect both upon the recovery and the grade inthe final concentrate.

in this example the fuel oil appears to act as a modifier and it provednecessary closely to control the quantity. Amounts greater than about3%: pounds per ton tended to depress the iron minerals whereasquantities smaller than 1 pound per ton, did not produce any measurableimprovement over cases where fuel oil was not used at all.

The fatty acid may be used in moderately higher amounts than thatindicated without any deleterious result, however, when the amount usedis decreased the effect of starvation is surprisingly a drop in recoveryaccompanied by a drop in grade. This is in contravention to conventionalflotation where normally starvation of the pulp with respect tocollecting agent produces an increase in the grade accompanied by a dropin the recovery. The petroleum sulfonatc appears to act as a substitutefor fatty acid and equivalent results can be achieved by reducing thefatty acid and increasing the petroleum sulfountc. This substitution isdesirable mainly because of he relatively low cost of petroleumsulfonate compared to that of fatty acid. The extent to which thissubstitution may safely be made without adversely affecting themetallurgy has not yet been determined.

The effect of the initial pli-i during the initial flocculation stage isquite marked. Too low an initial pi-i results in poor activation of themetallic oxides wherein during the cleaning stages these minerals tendto drop too rapidly resulting in low recovery and lowgrade concentrates,while too high an initial pi-l results in depression of the metallicoxides.

in this example the initial pit of the initial flocculation stage wasapproximately 6.45" rising at the end to 6.6. During the finalconditioning stage the pi i was at 7.35 which was the pH at whichinitial flotation was carried out. Departure up or down from this lastpH was found to have a deleterious effect, giving a lower gradeconcentrate when lower and a reduction in both recovery and grade whenappreciably higher.

EXAMPLE IV in this example and in example V the ore tested was an ironare in which the mineral constituent was principally martite withapproximately 1 1 percent of the total iron as magnetite, a minor amountof hematite. and up to about 5 percent in the form of iron silicate.

A sample of the ore (test 1 18) was ground for minutes in a laboratoryball mill at 60 percent solids in the present of 4.7 pounds per ton ofsodium silicate to produce a pulp in which the ore was effectivelydispersed. 2.2 pounds per ton of fatty acid (Acintol, a product of theArizona Chemical Company) was added and the pulp was conditioned for 10minutes to activate the mineral constituents thereof. Then 1.33 poundsper ton of sulfuric acid was added in four equivalent portions over 16minutes of conditioning time at 4 minute intervals. The initial pHbefore the addition of the sulfuric acid was 7.7 and thereafter the pHafter each addition of sulfuric acid was 7.4, 7.1, 7.0 and 6.8. Thefinal pH of the pulp after 16 minutes of conditioning was 6.9 at whichtime the mineral constituents were effectively flocculated.

Then 1.83 pounds per ton of sodium silicate was added bringing the pH to7.1. The pulp was conditioned for 9 minutes with the addition ofone-half pound per ton of sodium silicate after 3 minutes and anotherone-half pound after 6 minutes. The final pH after 9 minutes ofconditioning was 7.25 and the pulp was differentially fiocculated inthat the gangue materials were effectively dispersed and the desiredmineral constituents were flocculated. The pulp was then subjected toflotation in a Fagergren flotation cell with four stages of cleaning andthe addition of one-half pound per ton of sodium silicate between thefirst, second and third cleaners and one fourth pound per ton betweenthe third and fourth cleaners.

The flotation resulted in a concentrate having a grade of 65.71 percentiron at a recovery of 74.80 percent in the open circuit. The roughertailing combined with the first cleaner tailing represented 35.36percent by weight and contained 5.38 percent of the total iron. Thecleaner concentrate analyzed 4.07 percent SiO 0.12 percent CaO and 0.38percent MgO. On an ore of this type where no previous desliming had beencarried out the metallurgy is to be considered as outstanding.

EXAMPLE V A sample of the same ore as that used in example IV wasemployed in test no. 123. In this case the conditions and procedure werethe same as those of example 1V except that the grinding time was 22minutes and instead of 2.2 pounds per ton of fatty acid as a collectingagent there was used 0.79 pounds per ton of fatty acid together with2.78 pounds per ton of petroleum sulfonate (899 American Cyanamid)following the activation cycle the pulp was subjected to the same acidflocculation cycle and differential dispersion and flocculation cycle asin example IV.

The flotation produced a concentrate assaying 65.96 percent iron at arecovery of 74.12 percent in the open circuit. The rougher tailingcombined with the first cleaner tailing was 32.66 percent by weightcontaining 5.81 percent of the total iron content.

This test and that described in Example IV approached the optimummetallurgy for this particular ore. This ore was characterized by beingdifficult to disperse effectively, it having been found advantageous toadd the dispersing agent to the mill in order to avoid long conditioningtimes to achieve dispersion. The quantity of dispersing agent employedwas quite critical, larger quantities than that indicated tending todepress the mineral constituents and lower quantities resulting in pooractivation of the iron minerals.

The ore was further characterized by the fact that under the conditionsof operation effective activation could not be achieved until the orehad been brought into an effectively dispersed condition. Consequentlythe collecting agent when added to the mill along with the dispersingagent resulted in substantially poorer metallurgy with higher tailingslosses, lower grade concentrate and a lower recovery. Similarly wherethe dispersing agent and the collecting agent were both added togetherin a conditioning stage following grinding the same poor results wereobtained. The initial pH during the differential dispersion andflocculation cycle was shown to be critical and where the initial pH wasdropped lower than that indicated both grade and recovery suffered. Withthis ore the quantities of fatty acid and petroleum sulfonate were foundto be optimum at the values indicated but minor variations in quantityeither up or down did not seriously affect the metallurgy achieved.

EXAMPLE VI Ore Description This ore had a head value of approximately 32percent iron with approximately 66 percent of the iron minerals presentas hematite and 34 percent present as goethite.

The grinding cycle of the testing program in all cases was carried outin a laboratory rod mill.

At a grinding time of 28 minutes and 60 percent solids the following wasthe screen analysis of the product produced.

Percent weight +325 mesh 11. 45

325+4OO mosh l 4. 2O

-400+500 mesh :0. 10

500 mesh 64. 25

Total 100. 00 Effect of Conditioning Time in the Second Cycle of theFour- Cycle Circuit The grinding time in tests 153, 154 and 158 was 32minutes using 8.3 pounds of sodium silicate per long ton of ore added atthe beginning of the grinding cycle. In the terminology used thegrinding cycle would correspond to the No. 1 cycle in the effectivedispersion of the ground pulp.

The collector-modifier reagents to the second cycle were in all cases1.04 pounds Acintol FA2, 1.53 pounds 899 and 3.0 pounds of fuel oilrespectively per long ton of solids.

The third stage, in all cases, consisted of stage addition of 1.08pounds sulfuric acid per ton and a conditioning period of 16 minutes.

The fourth stage used 5.56 pounds of sodium silicate per ton, using 8minutes conditioning in 153 and 154, and 6 minutesin 158.

All test used five cleaner stages following the rougher float.

The pH by the beginning of stage 2 was 8.45. The lowest pH recorded instage 3 was 6.85 and ended at pH 7.0.

The pH in stage 4 was 8.45.

In test 158 with 8 minutes conditioning in the second stage, theconcentrate grade was 6.94 percent iron, containing approximately 73percent of the total iron. In test 153 with 12 minutes conditioning inthe second stage, the concentrate grade was 61.75 percent iron,containing approximately 74 percent of the total iron. ln test 154 with16 minutes conditioning in the second stage, the concentrate grade was58.56 percent iron, containing approximately percent of the total iron.

For effective cleaning of the rougher concentrate there was littledifference between the 8 minutes and 12 minutes in this activationstage. However, the' curve broke between 12 minutes and 16 minutes withthe activation extending to a higher range of the iron particlestogether with part of the host rock materials.

EXAMPLE VII Effect of Excessive Dispersion in Final Cycle ln comparativetests and 205 the reagents and conditioning times were the same with theexception of the amount of sodium silicate used in the last cycle of thefour cycle circuit. The grinding time was 28 minutes with 8.3 pounds ofsodium silicate and 0.7 pounds of sodium sulfate respectively per ton ofore added to the beginning of the grinding cycle. Stage 2 consisted of10 minutes conditioning using 1.83 pounds fatty acid (Acintol FA2.) 1.11pounds of petroleum sulfonate (899) and 3 pounds of fuel oilrespectively per ton of solids. Stage No. 3 used 16 minutes conditioningwith stage addition of 1.94 pounds sulfuric acid per ton. Stage 4consisted of 8 minutes conditioning with half of the sodium silicateadded at the beginning and the other half added at the end of 2 minutesconditioning for a total of 8 minutes conditioning time. In test 195,6.66 pounds of sodium silicate per ton was used and in test 205 7.77pounds sodium silicate per ton was used.

In test 195 the rejection in the rougher and first cleaner tailings was42.8 percent by weight, analyzing 5.76 percent iron. In test 205 therougher tailings rejection alone was 34.4 percent by weight, analyzing6.13 percent iron, showing a higher iron loss at a lower percentrejection and illustrating the detrimental effect of excess dispersionin this cycle.

EXAMPLE VIII The Effect of the Use of a Wetting Agent in the GrindingCir cuit In tests 229 and 230 the grinding cycle was 45 minutes and intest 229 Dow lBenax 2A-1 which is described as a wetting agent was addedat the beginning of the grinding cycle using 0.10 pounds per ton ofsolids. In test 230 no reagent addition was made to the grinding cycle,depending entirely upon the natural dispersion of the pulp in bothcases. The second cycle in both cases consisted of 8 minutesconditioning using 2.62 pounds of fatty acid (Acintol FAZ) 1.1 1 poundsof petroleum sulfonate (899) and 3 pounds of fuel oil respectively perton. The third cycle in both cases was 16 minutes using stage additionof 1.94 pounds per ton of sulfuric acid. In addition, in test 229 sodiumfluoride was added at the beginning of this cycle at the rate of 0.84pounds per ton. Stage 4 consisted of 11 minutes conditioning in bothcases with stage addition of 9.15 pounds per ton of sodium silicate. Intest 229 the tailings rejection was 36.5 percent by weight analyzing3.78 percent iron while in test 230 the tailings rejection was 36.4percent by weight analyzing 6.29 percent iron.

Previous testing had indicated that the use of the electrolyte in theacid circuit had very little effect on the iron activation, indicatingthat the use of a wetting agent in the grinding circuit where nodispersal agent was used resulted in a surprising increase in the ironactivation and in the host rock depression.

EXAMPLE IX Effect of Using Two Stages only Following the Grinding StageIn test 243 a 28 minute grinding cycle was used with no added reagents.In the cycle following grinding 20 minutes conditioning was used withthe addition of 3.66 pounds of fatty acid (Acintol FAZ) and 3 pounds offuel oil respectively per ton. The water pH was 7.05, and minutes afterthe addition of the reagents the pH of the pulp was 6.8. At the end ofthe minutes conditioning cycle the pH was 7.3. Following thisconditioning stage 2.78 pounds of sodium silicate per ton was added,bringing the pH to 8.1 and the conditioning time was 8 minutes.

After six cleaners the concentrate grade was 60.7 percent iron at arecovery of 79.8 percent.

In comparing this test to test 254 wherein the grinding time was 28minutes without reagent addition, the second stage was 8 minutes withthe same fatty acid and fuel oil addition followed by the normal thirdstage using 0.7 pounds per ton of sulfuric acid and the fourth stageusing a 21 minute conditioning .cycle and 5 pounds per ton of sodiumsilicate. After six cleaners the concentrate grade was 61.1 percent ironwith 91 percent of the total iron in the concentrate showing a markedimprovement in metallurgy over the twocycle stage following grinding.However, considering that in test 243 further research, particularlywith the last cycle, could improve these results on some ores and undercertain plant conditions of water supply and soluble salts, it couldresult in acceptable metallurgy.

EXAMPLE X The Use of Sodium Hydroxide for Controlled pH and FinalDispersal of the Pulp iii.

In test 244 a 28 minute grind was employed without any reagent additionto the grinding stage. The cycle following grinding was 8 minutes withthe addition of 3.66 pounds of fatty acid (Acintol FAZ) and 3 pounds offuel oil respectively per ton. The pH after the addition of the reagentswas 6.8. The next cycle was 12 minutes conditioning with the stageaddition of 1.67 pounds of sulfuric acid. The lowest pH recorded was6.00. The next cycle consisted of 7 minutes conditioning with theaddition of 0.833 pounds of sodium hydroxide per ton. The pH at the endof this cycle was 8.05. Seven cleaners were employed following therougher float resulting in a final concentrate analyzing 61.41 percentiron and containing 88.3 percent of the total iron, showing excellentmetallurgy in the open circuit worlt. However, the froth was on thetough side and without a further modifier could result in a problem inplant practice in final grade control.

EXAMPLE XI The following test used the four-cycle circuit wherein anultrafine grind was used with a grinding cycle time of45 minutes at 60percent solids with no reagent added to the grinding cycle. The secondstage was 8 minutes conditioning with 3.66 pounds of Acintol FAZ and 3pounds of fuel oil respectively per ton of solids. The pH during thiscycle was 6.8. The third cycle was of 12 minutes duration and used 1.1 1pounds of sulfuric acid per ton in stage addition. The lowest pl-Irecorded was 6.05. The fourth stage was 7 minutes conditioning withstage addition of 8.88 pounds sodium silicate per ton. The followingmetallurgy was attained:

TEST 235 Analysis, Percent Percent percent Fe distri- Product weighttotal Fe bution Cleaner concentrate 42. 8 G2. 15 82. 1 No. 6 cleanertails" 3. 2 49. 51 4. 7 No. 5 cleaner tails 2. 1 32. 2. 1 No. 4 cleanertlnls 2. 8 26. 14 2. 3 No. 3 cleaner tails 4. 4 18. 41; 2. 5 N0. 2cleaner tails 6. 9 10. 29 2. 2 N0. 1 cleaner tails 12. 4 5. l7 2. 1Rougher tails 25. 4 2. 59 2.0

Total 100. 0 100. 0

NOTE: Calculated heads=32.53% total Fe.

EXAMPLE Xll An appreciably coarser grind was used in this test than inexample XI as the grinding period was only 28 minutes. No reagents wereadded to the grinding circuit and the second cycle of fatty acid(Acintol FAZ) and fuel oil addition was identical to example XI. In thethird cycle the conditioning time was 12 minutes as in example XI.However, sulfuric acid was reduced to 0.7 pounds per ton. The majorchange was in the fourth cycle in which the conditioning time wasincreased to 21 minutes and the sodium silicate added in stages for atotal of 5 pounds per ton as against the larger amount used in exampleXI for the shorter conditioning period of 7 minutes. The rougherconcentrate was water cleaned only using seven cleaners. It will benoted that the final concentrate analyzed 61.67 percent higher for therecovery of 89%. percent of the total iron in the concentrate. With theloss of ignition of approximately 3 percent on this concentrate afterpcllctizing this concentrate grade would increase to approximately 63.6percent iron, which is an outstanding grade for the recovery involved inthe open circuit text. It will further be noted that in test 235 theoriginal tailings rejection was 37.8 percent by weight carrying 4.1percent of the total irons. In test 254 the same rougher tailings plusfirst cleaner rejection was 40.3 per cent by weight, carrying only 3.4percent ofthe total iron. This comparative metallurgy basicallyextending the time of the last conditioning cycle in test 254 with asmaller amount ofthe dispersing agent, that is, sodium silicate,illustrates the high importance ofthe time factor ofthis last cycle.

TEST 254 Analysis, Percent Percent percent Fe distri- Product weighttotal 11 bution Cleaner concentrate 413. 6 61. (i7 89. 5 No.7 cleanertails... 1. 2 40. (A. 1. 5 No. 6 cleaner tails. 0. St 33. 65 1. No.cleaner tials. 1.3 223. S) 1. 2 No. 4 clcnner tails. 1. 7 18. 5G 1. (INo. 3 cleaner tails. 2. J 13. 72 1. L No. 2 cleaner tails. 5. 1 .6 1. L.No. 1 cleaner tails. 12. 1 l 1. 7 Rougher tails 28. 2 1. 7

Total 100.0 100. U

NOTE: Calculated heads=32.10% total Fe.

EXAMPLE Xlll A sample of uranium ore from Blind River Ontario ground for14 minutes at 60 percent solids in a laboratory rod mill with theaddition of 2.5 pounds per ton ofsodiurn chloride as an electrolyte. Thegrind screen analysis was 60 percent minus 200 mesh. The ground ore wasthen placed in a 600 gram Fagergren laboratory flotation cell and thedensity was decreased to approximately 40 percent solids. The pl l ofthe water was 7.15. 1.23 pounds per ton of sodium silicate was added andthe pulp was conditioned for 10 minutes to achieve effective dispersion.2.73 pounds per ton offatty acid (Acintol FA2) and 3.9 pounds per ton offuel oil were added and the pulp was conditioned for minutes at the endoi which time the pH was 6.95 and the pulp was in final condition forflotation and was floated.

The head value of the ore was 0.17 percent U 5) and the weight of thetailings was 62.4 percent by weight analyzing 0.039 percent U 0 for atailing-s loss of 14.3 percent.

An identical test carried out using only 0.615 pounds per ton of sodiumsilicate produced a tailings weight of 78.5 percent analyzing 0.112percent U 0, for a tailings loss of 51.7 percent. In a third identicaltest 1.845 pounds per ton of sodium silicate was used producing atailings weight of 84.1 per cent analyzing 0.137 percent U 0 for atailings loss of 67.7 percent.

This testing indicated the criticality of the quantity of dispersingagent with respect to the achievement of effective dispersion of thisore, too much or too little dispersing agent resulting in a hightailings loss.

Application ofthe Process to Typical Plant Flow Sheets The process ofthe invention may be applied to plant flow sheets in a number ofdifferent ways depending upon the comminution circuit which is used. Theapplication of the process will be described in connection with fourbasically different comminution circuits.

Several examples of plan flow sheets are illustrated in the accompanyingdrawings wherein:

FIG. 1 is a block flow sheet illustrating a typical grinding circui't;

FIG. 2 is a block flow sheet illustrating another typical grindingcircuit;

FIG. 3 is a block flow sheet ofa further grinding circuit;

FIG. 4 illustrates still another comminution circuit; and

FIG. 5 is a block flow diagram illustrating the four conditioning cyclesof the present invention together with a typical flotation circuit.

Description ofComminution Circuits A. One comminution circuit isillustrated in FIG. 1 and con sists of feeding the run of mine ore to aprimary crusher 1d the product of which is fed to a wet autogenous mill12, operating in closed circuit. Alternatively the wet autogenous millmay be replaced by a conventional rod mill, ball mill in closed circuitwith its classifier in which case an appropriate number of additionalstages of crushing would of course be necessary. The product from thewet autogenous mill 12 or rod millball mill circuit is fed to aclassifier 14 from which the oversize 15 is returned to the inlet sideof the ball mill circuit. The undersize which will generally be a pulpcontaining from about 12 to 25 percent solids is treated with aflocculating agent and passed to a thickener 17 from which the overflowis passed to the plant water supply system 18. The underflow 19 "fromthe thiclzner 7.7 which will be at between 50 and 70 percent solidsserves as the feed for the flotation plant.

In a second type of comminution circuit (see FIG. 2), the run-of-miiieore is passed to a primary crusher 20 the product 2?. ofwhich is feed toa dry autogenous mill 22 which is either in open or closed circuit witha dry classifier, the product 23 of which is fed to a closed circuitball mill 2 the product 25 of which is fed to a classifier 26 from whichthe oversize 27 is recirculated to the ball mill inlet. The undersize 28from the classifier 26 which is at approximately 20 percent solids istreated with a flocculating agent and fed to a thickener 29 from whichthe overflow 3G is returned to the plant water supol and the underflow31. which is in the form of a pulp containing from about 50 to 70percent solids is used as the flotation plant iced.

C. As an alternative to 15 using a dry autogenous mill in either open orclosed circuit for primary grinding the product of the dry autogcnousmill 22 (see FIG. 3) may be fed to an open circuit ball mill 32. Theoutput of the open circuit ball mill consists ofa pulp containingapproximately 50 to 70 percent solids and is used as the flotation plantfeed. Alternatively with certain ores it is possible and in many casesadvantageous to employ the open circuit ball mill for purposes ofcarrying out one or more of the stages of conditioning which wouldnormally be carried out in the flotation plant:

Alternative 3 On certain ores it would be advantageous to add dispersingagent to the feed end of the ball mill and to maintain pH controlarranged to maintain a controlled pH at the mill outlet. Thisalternative is advantageous in cases where the ore has a slime factorwhich is particularly deleterious to the flotation unless effectivelydispersed in a controlled pH range prior to activation ofthc desiredrecoverable constituents.

Alternative 2 In certain cases it may be desirable to add bothdispersing agent and a collecting agent to the feed end of the millagain while maintaining pH control. This procedure is advantageous incases where activation of the desired mineral constituents can beobtained at the same time that dispersion of the waste host rockmaterials is taking place. This is generally so when the desired mineralconstituents are not readily depressed by the dispersing agent withinthe pH range used, and where it is employed the conditioning cycles ofeffective dispersion, partial activation and partial flocculation occurwithin the ball mill during the grinding process to produce a grindingplant product which is already in partially activated and flocculatedcondition.

Alternative 3 In some cases where the nature of the ore and otherconditions are such as to produce effective dispersion without theaddition of dispersing agent it is advantageous merely to add collectingagent to the feed end ofthe ball mill and to maintain the appropriate pHcontrol, which is preferably slightly on the acid side. Where thisalternative procedure applies the ball mill product is again aconditioned partially activated and flocculated pulp.

D. Another alternative for ore preparation is illustrated in FIG. 4where a dry closed circuit autogcnous mill is used for primary grindingand the mill product is passed through a dry classifier to produce afines fraction 44 consisting of approximately 50 percent by weight ofthe total material which is ofa size range suitable for flotation and anoversize fraction 45 consisting of approximately 50 percent by weight ofthe total material which is then fed to a secondary closed circuit ballmill 46, the product 47 of which is passed to a classifier 48 from whichthe oversize 49 is returned to the inlet side of the ball mill, and theundersize 50 which consists of a pulp containing about 50 percent byweight of the total primary mill product at approximately 20 percentsolids is combined with the dry classifier fines to form product 51which is passed to an agitator 52 to produce a grinding plant product atabout 60 percent solids. Under some conditions this may be too high anddilution of the pulp down to 35 to 50 percent solids may be desirable.Description of Conditioning and Flotation Circuits and Their Applicationto Flotation Plant Feed Prepared as Above a. Where the flotation plantfeed is prepared in a wet autogenous or conventional closed grindingcircuit according to (A) above, it will contain the flocculating agentwhich was added ahead of the thickener and there are three generalapplications of the process of the invention, the selection of whichwill depend upon the nature of the flocculating agent which has beenused and the nature of the ore and plant water supply.

I. Where the flocculating agent which has been used prior to thethickener is a persistent flocculating agent which forms a flockdifficult to break up by mechanical means such as passage through apump, it will be necessary to employ a dispersing agent and to conditionthe pulp to achieve effective dispersing thereof prior to the additionof a collector. This conditioning cycle will normally require theadjustment of the pH by the addition of sodium hydroxide or sulfuricacid to within the range of from about 7.0 to 8.9 with a conditioningtime of from about 3 minutes to about l6 minutes in conditioning stage50 (see FIG. The pulp is then subjected to an activation cycle inconditioning stage 51 wherein the collecting agent is added and afurther period of conditioning of from about i 3 minutes to about 16minutes is carried out at a pH of from about 6.7 to 8.7. The pH of thepulp will then be reduces if necessary to bring it within the range offrom about pH 5.0 to 7.2 and a further period of conditioning inconditioning stage 52 of from about 8 minutes to about 16 minutes iscarried out. Upon completion of the foregoing cycle the pH will beadjusted if necessary to bring it within the pH range of from about 6.5to 8.5 with the addition of dispersing agent and the pulp is conditionedin conditioning stage 53 for a period of from about 3 minutes to about25 minutes to bring about differential flocculation by dispersing thegangue materials while bringing about final heavy flocculation of thedesired mineral constituents. The conditioning stages 50, 51, 52 and 53may employ conventional flotation plant equipment and may each consistof several conditioning units.

The pulp is then subjected to flotation which is basically the same forall of the different conditioning procedures and consists of a rougherfloat 54 to produce a final rougher tailing 55 which is passed to thetailings pond 56 and a rougher concentrate 57 which may be followed bycleaners 58 which may contain up to seven cleaning stages with orwithout conditioning between some or all of the stages to produce afinal concentrate 59 which is passed to further processing 60 such asthickeners prior to filtering or alternatively directly to filtering andcombined cleaner tailings 61 which will normally be returned to theclassifier 14 of mill 12 (see FIG. 1). In some cases the first or secondcleaner tailing may be of sufiiciently low value to be rejected with therougher tailing as a final tailmg.

. Where the ore is such that the mineral constituents are not depressedwithin the concentration of dispersing agents required to effectivelydisperse the host rock, the first two cycles and 51 described in (I) maybe carried out together. In this case the dispersing agent and thecollector will be added to the pulp for a combined dispersing andactivation cycle which will be carried out at a controlled pH of fromabout 6.7 to 8.9 for a period of from about 4 minutes to 16 minutes.This cycle will be followed by a flocculating cycle 52 in which the pHof the pulp is reduced if necessary by the addition of e.g. sulfuricacid to within the range of pH 5.0 to 7.2 and a period of conditioningfrom about 8 to about 16 minutes will be carried out to achieve heavyflocculation. Following the flocculation cycle the pH of the pulp willbe adjusted if necessary with, e.g. sodium hydroxide to bring it withinthe range of from about 6.5 to about 8.9 and conditioning stage 53 iscarried out for a period of from about 3 to 25 minutes with or withoutthe addition of additional dispersing agent to bring about differentialflocculation by effective dispersion of the gangue materials with finalheavy flocculation of the desired mineral constituents. This last cycleis then followed with flotation similar to that described in (I).

(III) Where the flocculating agent used in advance of the thickener is anonpersistent flocculating agent which produces flocks which are readilybroken down by mechanical agitation such as a guargum in slightly acidcircuit, the pulp by the time it arrives at the flotation plant may bein effectively dispersed condition. In this case the pulp will be passeddirectly from the grinding plant 61 to an activation stage 52 where withthe pH adjusted if necessary to a pH range of from about 5.0 to about7.2 the pulp is subjected to from about 4 minutes to 20 minutesconditioning in the presence of the collecting agent. In this case theactivation and flocculation stages may be combined, since the additionof collecting agent will tend initially to lower the pH whileacid-consuming constituents in the ore will tend to slightly raise thepH as the conditioning proceeds. Thus, at the end of the conditioningperiod the mineral constituents will be in an effectively flocculatedcondition. The pH of the pulp will then be adjusted if necessary towithin the range of from about 7 to about 8.9 with the use of analkaline agent and the pulp will be conditioned in a conditioning stage53 to bring about partial dispersion in the presence of a dispersingagent. In some cases the dispersing agent may also be used as analkaline agent, e.g. in the case of sodium silicate alone, sodiumhydroxide alone or sodium silicate and sodium hydroxide. The pulp isthen subjected to flotation which will suitably be of the same type asdescribed in (I).

b. Where the flotation plant feed is prepared with a grinding circuit asdescribed in B, the flotation plant feed will contain the flocculatingagent added prior to the thickener 29. Conditioning procedures I, II orIII will be applied to this material in accordance with the sameprinciples as those outlined in (a).

It should be pointed out that in some cases it may be possible tooperate the thickeners referred to in (A) and in (B) without the use offlocculating agents in which case partial flocculation of the materialtakes place in the thickener due to the conditions of the mill solutionand the otherwise normal or adjusted pH in the thickener. In such a casethe particular plant may find it more economic to eliminate the use ofthe flocculating agent and take a comparatively small loss in the valuedmineral constituents that will occur in the overflow in the thickeneroverflows which in this case would be taken to the tailings pond or atailings thickener where it would be flocculated probably with the planttailings and sent directly to waste. The flotation plant feed producedby thickening in the foregoing manner would be treated by any one of(I), (II) or (III) depending upon the degree of flocculation and thestrength of the floccs initially formed.

c. Where the flotation plant feed is prepared by a dry autogenous millfollowed by an open circuit ball mill as in C above in the firstinstance where no reagents are used in the open circuit ball mill, theconditioning procedure followed will be (I), (II) or (III) dependingupon the condition of dispersion and flocculation which obtains in theflotation plant feed on its arrival.

Where alternative 1 has been applied and the dispersing agent added withthe feed to the ball mill under controlled pH the flotation plant feedwill arrive in effectively dispersed condition and depending upon thenature of the ore, procedure (lll) may be used (where the concentrationof dispersant in the pulp at the pH concerned does not interfere withflocculation of the mineral constituents).

Where altemative ore preparation procedure 2 is used with the ball millin open circuit and both a dispersing agent and a collecting agent arefed to the ball mill while maintaining pH control the flotation plantfeed will arrive at the flotation plant in flocculation condition, theconditioning stages of effective dispersion, activation and flocculation(Le. 50, 51 and 52) having been accomplished during the progress of thematerial through the open circuit ball mill. in this case, the flotationcircuit feed arriving from grinding plant 61 will be subjected directlyto a stage of conditioning 53 in the presence of a dispersing agent,preferably sodium silicate, for a period of from about 3 to aboutminutes at a pH within the range of from about 6.7 to about 8.5 forpurposes of bringing about differential flocculation wherein the ganguematerials are effective dispersed while the mineral constituents areeffectively maintained in flocculation condition. The pulp is thereaftersubjected to a flotation 54 with subsequent stages as described in (I).

Where the feed to the flotation plant has been prepared in accordancewith alternative 3 and only collecting agent has been added to the ballmill fed under pH control the flotation plant feed will also arrive atthe flotation plant under conditions of flocculation. Once again theconditioning cycles of effective dispersion, activation, andflocculation will have been accomplished in the ball mill where slightlyacid conditions will have prevailed. in this instance the flotationplant feed will again be subjected directly to a stage of conditioning53 to bring about differential flocculation by maintaining the gangueefi'ectively dispersed with final heavy flocculation of the desiredmineral constituents. However, conditions may be such that it may not benecessary to add a specific dispersing agent since the conditionsalready present in the pulp may permit the desired effect to be achievedat the initial pH of the pulp. It is unlikely however that suchconditions will prevail over any substantial period of operation in anyparticular plant because of variations in the nature of the ore and inthe water supply. Consequently it will normally be desirable to addsufficient alkaline agent to elevate the pH to the appropriate value(the preferred range being from about 7.2 to 8.5) and it will usually bedesirable either that the alkaline agent used by itself be a dispersingagent, e.g. sodium silicate or sodium hydroxide or to add a controlledamount of dispersing agent as well as an alkaline agent. Followingconditioning in the above controlled conditions for a period of fromabout 3 to 25 minutes the pulp will be subjected to flotation 54 and thesubsequent stages described in (l). d. Where the flotation plant feed isprepared in accordance with the comminution procedure described in Cabove, the flotation plant feed will arrive at the flotation plantwithout any reagents having been added to it during the comminutioncycle with the exception of dissolved reagents in the normal mill watersupply. in this case depending upon the nature of the ore and of themill water supply any one of procedures (I), (II) or (ill) would beappropriate.

The above-described comminution procedures are the most commonly metwith in plants where the present invention is likely to findapplication. It will be apparent however that the process of theinvention involving the four cycles of effective dispersion, activation,flocculation and difierential dispersion and flocculation is readilyadaptable to other plant flow sheets with which it may be integratedwhere conditions permit with the comminution circuit employed. It isimmaterial to the effectiveness ofcarrying out of the process whetherone or more of the conditioning cycles are carried out within thegrinding circuit or whether all four are carried out externally to thegrinding circuit in the flotation plant. Generally speaking savings inplant equipment and operating costs are achieved by integrating theconditioning process into the comminution circuit to the extent that itis possible to do so under any given conditions with any particular ore.

In addition to cases where the invention is applied to the product of agrinding plant there are many instances where it may be applied to thetreatment of materials which are already in comminuted or naturallyfinely divided condition e.g. tailings piles or slimes from an existingplant that uses desliming procedure ahead of the normal recovery plantas well as in the case of some beach sands and natural occuring clayscontaining desired mineral constituents such as vanadium oxides. in suchcases the pulp formed from the material to be treated will usually besimilar in condition to one the various pulps produced by the grindingcircuits already described, and the conditioning procedures to beemployed according to the invention will be the same for pulps ofsimilar type.

In the foregoing description of the application of the invention thevarious optimum conditioning times and reagent additions are based onthe pulp being at approximately 40 percent solids, at temperatures offrom 7C to 21C with high impeller speeds in the conditioning cycles.Increases or decreases in the pulp density in one or more of theconditioning cycles and increases or decreases of the conditionerimpeller speeds, will affect the optimum time and reagent balance in anyparticular case. Furthermore temperatures outside the above range can beexpected to have an effect upon the optimum times of the variousconditioning cycles and upon the optimum reagent balance. The operatingconditions employed throughout the test work reflected in the examplesare generally representative or normal operating plant conditions and nodifficulty should be experienced in adapting the process of theinvention to conditions of temperature, plant water conditions anddifferent forms of conditioning equipment which are within the range ofwhat is generally accepted as normal plant practice. Changes inoperating conditions may bring about changes in the optimum procedureaccording to the invention and it is desirable according to theinvention, in plant practice to control the conditions so as to avoidmajor fluctuations within the circuit. Water temperature, pulp densityand the pH in each conditioning cycle may be automatically controlledwithin the effective limits required for optimum plant operationemploying conventional plant control devices.

What I claim as my invention is:

1. A process for the flotation of metallic oxides and metallic oxideswith water of crystallization in chemical combination occuring in oresas finely disseminated minerals requiring fine grinding for theliberation of said minerals from essentially undeslimed partiallydispersed pulps thereof comprising; conditioning a pulp of an orecontaining one or more of said minerals in a state of subdivision wherethe mineral content thereof is substantially liberated with apredetermined amount of a collecting agent for the desired mineralvalues thereof at a substantially neutral pH; then at a pulp pl-l withinthe range of from substantially neutral to about 5.0, conditioning thepulp until substantial flocculation of said mineral values has occurred;then in a final conditioning stage at a pH of from about 6.5 to about8.9 conditioning the pulp with the addition of a dispersing agent tobring about effective dispersion of the gangue materials while themineral values remain flocculated; and then subjecting the thusconditioned pulp to flotation to produce a concentrate of the mineralvalues therein.

2. A process as defined in claim 1 in which the pulp initially containsa controlled amount, predetermined by experiment, of an electrolytewhich is free of ions deleterious to flotation.

3. A process as defined in claim 2 wherein the electrolyte is sodiumsulfate.

4. A process as defined in claim 2 wherein the electrolyte is sodiumchloride.

5. A process as defined in claim 2 wherein the electrolyte is sodiumfluoride.

6. A process as defined in claim 1 wherein the pulp initially contains acontrolled amount, predetermined by experiment, of a wetting agent whichis free of ions deleterious to flotation.

7. A process as defined in claim 1 wherein the pulp initially contains acontrolled amount, predetermined by experiment, of a dispersing agent.

8. A process as defined in claim 7 wherein the dispersing agent issodium silicate.

9. A process as defined in claim 1 wherein the mineral values are iron.

10. A process as defined in claim ll wherein the mineral values areuranium.

11. A process as defined in claim 1 wherein'the mineral values are ironand the flocculation stage of conditioning is carried out at an initialpH, predetermined by experiment, of from about 6.2 to about 7.2 for aperiod of approximately 12 minutes.

12. A process as defined in claim ll wherein the final stage ofconditioning is carried out at a controlled pH predetermined byexperiment, within the range offrom about 7.2 to about 8.5 in thepresence of a controlled amount, predetermined by experiment, of sodiumsilicate for a period predetermined by experiment of from about 3 toabout 25 minutes.

13. A process as defined in claim 1 wherein the mineral values are ironand the final stage of conditioning is carried out at a controlled pH,predetermined by experiment, of from about 6.7 to 8.5 in the presence ofa controlled amount, predetermined by experiment of a dispersing agentfor a period, predetermined by experiment of from about 4 to about 24minutes. i

14. A process for the flotation of metallic oxides, and metallic oxideswith water of crystallization in chemical combination occurring in oresas finely disseminated minerals requiring fine grinding for liberationof said minerals from essentially undeslimed pulps thereof, comprising;bringing about, in a pulp of an ore containing one or more of saidminerals in a state of subdivision where the mineral values thereof aresubstantially liberated, effective dispersion of said ore; then in anactivation conditioning stage conditioning said effectively dispersedore in said pulp with a predetermined amount of a collecting agent forthe mineral values thereof; and then in a flocculating conditioningstage at a pulp pH within a range in which the mineral values thereofwill flocculate in the presence of the collecting agent used,conditioning the pulp until substantial flocculation of said mineralvalues has occurred; then in a final conditioning stage at a pulp pHwithin the optimum range of pH for flotation of the mineral valuesthereof, conditioning the pulp with the addition of a dispersing agentto bring about effective dispersion of the gangue materials withoutdeflocculating the mineral values; and then subjecting the thusconditioned pulp to flotation to produce a concentrate of the saidmineral values.

15. A process as defined in claim 14 wherein said effective dispersionof said ore is brought about in the presence of a controlled amount,predetermined by experiment of at least one reagent selected from thegroup consisting of wetting agents, electrolytes and dispersing agentswhich are free from ions deleterious to flotation.

16. A process as defined in claim 14 wherein the mineral values are ironand said effective dispersion of said ore is brought about in thepresence of a controlled amount, predetermined by experiment, of sodiumsilicate.

17. A process as defined in claim 14 wherein the mineral values are ironand said effective dispersion of said ore is brought about in thepresence of a controlled amount, predetermined by experiment, of sodiumsulfate.

18. A process as defined in claim 14 wherein the mineral values are ironand said effective dispersion of said ore is brought about in thepresence of a controlled amount, predetermined by experiment, of awetting agent which is free from ions deleterious to flotation.

19. A process as defined in claim 14 wherein the activation conditioningstage is carried out at an initial pH, predetermined by experiment,within the range of from about 6.7 to about 7.2 for a period of time,predetermined by experiment, of from about 4 to about 16 minutes.

20. A process as defined in claim 114 wherein the mineral values areiron and the activation conditioning stage is carried out at an initialpH, predetermined by experiment, within the range of from about 6.7 toabout 7.2 for a period of time, predetermined by experiment, of fromabout 4 to about 16 minutes.

21. A process as defined in claim 14 in which the flocculatingconditioning stage is carried out at an initial pH, predetermined byexperiment of from about 5.0 to about 6.5 for a period of time,predetermined by experiment, of from about 8 minutes to about 16minutes.

22. A process as defined in claim 14 in which the mineral values areiron and the flocculation'conditioning stage is carried out at aninitial pH, predetermined by experiment, of from about 5.0 to about 6.5for a period of time, predetermined by experiment, of from about 8minutes to about 16 minutes.

23. A process as defined in claim 14 wherein the final conditioningstage is carried out at an initial pH, predetermined by experiment,within the range of from about 7.2 to about 8.5 with the addition to thepulp of a controlled amount, predetermined by experiment, of sodiumsilicate and for a period of time, predetermined by experiment of fromabout 6 to about 21 minutes.

24. A process as defined in claim 14 wherein the mineral values are ironand the final conditioning stage is carried out at an initial pH,predetermined by experiment, within the range of from about 7.2 to about8.5 with the addition to the pulp of a controlled amount, predeterminedby experiment, of sodium silicate and for a period of time,predetermined by experiment of from about 6 to about 21 minutes.

25. A process for the flotation of metallic oxides, and metallic oxideswith water of crystallization in chemical combination occurring in oresas finely disseminated minerals requiring fine grinding for theliberation of said minerals from essentially undeslimed pulps thereof,comprising; bringing about, in a pulp of an ore containing one or moreof said minerals in a state of subdivision where the mineral valuesthereof are substantially liberated, effective dispersion of said ore;then in an activation conditioning stage conditioning said effectivelydispersed ore in said pulp with a predetermined amount of a collectingagent for the mineral values thereof; then in a flocculationconditioning stage at a pulp pl-l within a range in which the mineralvalues thereof will flocculate in the presence of the collecting agentused, conditioning the pulp with the addition of a dispersing agentuntil substantial flocculation of said mineral values and effectivedispersion of the gangue materials without deflocculating the mineralvalues has occurred; and then subjecting the thus conditioned pulp toflotation to produce a concentrate of the said mineral values.

26. A process as defined in claim 25 wherein said effective dispersionof said ore is brought about in the presence of a controlled amount,predetermined by experiment of at least one reagent selected from thegroup consisting of wetting agents, electrolytes and dispersing agentswhich are free from ions deleterious to flotation.

27. A process as defined in claim 25 wherein the mineral values are ironand said effective dispersion of said ore is brought about in thepresence of a controlled amount, predetermined by experiment, of sodiumsilicate.

28. A process as defined in claim 25 wherein the mineral values are ironand said effective dispersion of said ore is brought about in thepresence of a controlled amount, predetermined by experiment of sodiumhydroxide.

29. A process as defined in claim 25 where the mineral values are ironand said effective dispersion of said ore is brought about in thepresence of a controlled amount, predetermined by experiment, of sodiumsulfate.

30. A process for the flotation of metallic oxides and metallic oxideswith water of crystallization in chemical combination occurring in oresas finely disseminated minerals requiring fine grinding for theliberation of said minerals from essentially undeslimed pulps thereofcomprising; preparing a pulp of an ore containing at least one mineralselected from the class consisting of metallic oxides and metallicoxides with water of crystallization, which has been finely ground tosubstantially liberate the minerals thereof for the process offlotation, in which pulp ground ore is effectively dispersed fordifferential activation; conditioning said pulp with collector agentused for flotation of said minerals to differentially activate saidminerals and then adjusting the pH of the pulp to within the optimumrange for flotation of said minerals and depression of the gangue andconditioning said pulp for flotation in a final stage of conditioningwith the addition of dispersing agent whereby gangue materials in saidore are effectively dispersed while the said minerals remainflocculated; and then subjecting the thus conditioned pulp to flotationto produce a concentrate of said minerals.

31. A process according to claim 30 in which the pH range within whichsaid final stage of conditioning is carried out is from about 6.7 toabout 8.9 and the predetermined period of time of said final stage ofconditioning is a time predetermined by experiment within the range offrom 3 to 25 minutes.

32. A process as defined in claim 30 wherein the pulp contains acontrolled amount, predetermined by experiment, of an electrolyte whichis free of ions deleterious to flotation.

33. A process as defined in claim 32 wherein the electrolyte is sodiumsulfate.

34. A process as defined in claim 30 wherein the pulp contains acontrolled amount, predetermined by experiment of a dispersing agent.

35. A process as defined in claim 34 wherein the dispersing agent issodium silicate.

36. A process as defined in claim 30 wherein the mineral values areiron.

37. A process as defined in claim 30 wherein the mineral values areuranium.

38. A process as defined in claim 30 wherein the ore is an iron orewherein the mineral values in the ore are selected from the groupconsisting of hematite, specular hematite, magnetite, martite andgoethite.

39. A process as defined in claim 30 wherein the flotation reagent isselected from the group consisting of fatty acid, mixtures of fatty acidand petroleum sulfonate and mixtures of fatty acid and petroleumsulfonate and fuel oil wherein the fuel oil is present in amounts notexceeding pounds per ton of solids.

40. A process as defined in claim 30 wherein the conditioning withcollector agent is in an acid circuit and wherein said conditioningwithin the optimum range for flotation of said minerals and depressionof the gangue is in an alkali circuit.

41. A process as defined in claim 40 in which the ore is a readilydispersable iron ore wherein the dispersion of the ore for differentialactivation and the conditioning of the pulp with a collector agent todifferentially activate the minerals is combined in a single stage.

42. A process for the flotation ofmetallic oxides and metallic oxideswith water of crystallization comprising; wet grinding an ore containingone or more of said minerals in the presence of a quantity predeterminedby experiment of a dispersing agent and a quantity predetermined byexperiment ofa collecting agent for said minerals to produce a pulp ofsaid ore wherein liberated mineral content thereof is activated; then ata pulp pH within a range in which the mineral values thereof willflocculate in the presence of the collecting agent used, in aflocculation stage of conditioning, conditioning the pulp untilsubstantial flocculation of said mineral values has occurred; then at ahigher pulp pH within the optimum range of pH for flotation of themineral values thereof, in a final conditioning stage, conditioning thepulp to bring about effective dispersion of the gangue materials withoutdeflocculating the mineral values.

43. A process as defined in claim 42 wherein the ore is an iron orewherein the mineral values in the ore are selected from the groupconsisting of hematite, specular hematite, magnetite, martite andgoethite.

44. A process as defined in claim 42 wherein the flotation reagent isselected from the group consisting of fatty acid, mixtures of fatty acidand petroleum sulfonate and mixtures of fatty acid and petroleumsulfonate and fuel oil wherein the fuel oil is present in amounts notexceeding 5 pounds per ton ofsolid pulp.

45. A process for the concentration of iron ore occurring as finelydivided minerals of the class consisting of hematite, martite, goethite,magnetite and specular hematite requiring fine grinding for theliberation of said minerals from essentially undeslimed pulps, whichcomprises subjecting the ore to wet comminution in the presence of apredetermined amount of sodium silicate to produce an effectivelydispersed pulp of said ore; conditioning said ore in the presence of acollecting agent for the iron mineral present to cause flocculation ofsaid mineral; lowering the pH to neutral or slightly lower by theaddition of a suitable acid reagent; further conditioning the pulp inthe presence of a predetermined amount of sodium silicate for apredetermined period of time to maintain the gangue materials dispersedwhile the pH of said pulp rises to within the optimum range forflotation of the said iron mineral to effect and bring aboutflocculation of said iron mineral favorable for flotation; and thensubjecting the thus conditioned pulp to flotation to produce aconcentrate ofsaid iron mineral.

46. A process for the concentration of iron ore occurring as finelydivided minerals of the class consisting of hematite, martite, goethite,magnetite and specular hematite requiring fine grinding for theliberation of said minerals from essentially undeslimed pulps, whichcomprises subjecting the ore to wet comminution, adding to saidcomminuted ore a predetermined amount of sodium silicate to produce aneffectively dispersed pulp of said ore; conditioning said ore in thepresence of a collecting agent for the iron mineral present to causeflocculation of said mineral; lowering the pH to neutral or slightlylower by the addition of a suitable acid reagent; further conditioningthe pulp in the presence of a predetermined amount of sodium silicatefor a predetermined period of time to maintain the gangue materialsdispersed while the pH of said pulp rises to within the optimum rangefor flotation of the said iron mineral to effect and bring aboutflocculation of said iron mineral favorable for flotation; and thensubjecting the thus conditioned pulp to flotation to produce aconcentrate ofsaid iron material.

47. The improved process of claim 46 wherein the collecting agent is afatty acid collecting agent.

48. The improved process of claim 47 wherein in further conditioning thepulp the pH thereof is adjusted to within the optimum range forflotation by the addition of a reagent selected from the groupconsisting of a dispersing agent, a dispersing agent combined with analkali or an alkali dispersing agent.

49. The improved process of claim 46 wherein the collecting agentconsists of a combination of fatty acid collecting agent and petroleumsulfonate collecting agent.

50. The improved process of claim 46 wherein the collecting agent is acombination of fatty acid collecting agent, petroleum sulfonatecollecting agent and fuel oil.

51. The improved process of claim 46 wherein the collecting agentconsists of a combination of fatty acid collecting agent and fuel oil.

2. A process as defined in claim 1 in which the pulp initially containsa controllEd amount, predetermined by experiment, of an electrolytewhich is free of ions deleterious to flotation.
 3. A process as definedin claim 2 wherein the electrolyte is sodium sulfate.
 4. A process asdefined in claim 2 wherein the electrolyte is sodium chloride.
 5. Aprocess as defined in claim 2 wherein the electrolyte is sodiumfluoride.
 6. A process as defined in claim 1 wherein the pulp initiallycontains a controlled amount, predetermined by experiment, of a wettingagent which is free of ions deleterious to flotation.
 7. A process asdefined in claim 1 wherein the pulp initially contains a controlledamount, predetermined by experiment, of a dispersing agent.
 8. A processas defined in claim 7 wherein the dispersing agent is sodium silicate.9. A process as defined in claim 1 wherein the mineral values are iron.10. A process as defined in claim 1 wherein the mineral values areuranium.
 11. A process as defined in claim 1 wherein the mineral valuesare iron and the flocculation stage of conditioning is carried out at aninitial pH, predetermined by experiment, of from about 6.2 to about 7.2for a period of approximately 12 minutes.
 12. A process as defined inclaim 1 wherein the final stage of conditioning is carried out at acontrolled pH predetermined by experiment, within the range of fromabout 7.2 to about 8.5 in the presence of a controlled amount,predetermined by experiment, of sodium silicate for a periodpredetermined by experiment of from about 3 to about 25 minutes.
 13. Aprocess as defined in claim 1 wherein the mineral values are iron andthe final stage of conditioning is carried out at a controlled pH,predetermined by experiment, of from about 6.7 to 8.5 in the presence ofa controlled amount, predetermined by experiment of a dispersing agentfor a period, predetermined by experiment of from about 4 to about 24minutes.
 14. A process for the flotation of metallic oxides, andmetallic oxides with water of crystallization in chemical combinationoccurring in ores as finely disseminated minerals requiring finegrinding for liberation of said minerals from essentially undeslimedpulps thereof, comprising; bringing about, in a pulp of an orecontaining one or more of said minerals in a state of subdivision wherethe mineral values thereof are substantially liberated, effectivedispersion of said ore; then in an activation conditioning stageconditioning said effectively dispersed ore in said pulp with apredetermined amount of a collecting agent for the mineral valuesthereof; and then in a flocculating conditioning stage at a pulp pHwithin a range in which the mineral values thereof will flocculate inthe presence of the collecting agent used, conditioning the pulp untilsubstantial flocculation of said mineral values has occurred; then in afinal conditioning stage at a pulp pH within the optimum range of pH forflotation of the mineral values thereof, conditioning the pulp with theaddition of a dispersing agent to bring about effective dispersion ofthe gangue materials without deflocculating the mineral values; and thensubjecting the thus conditioned pulp to flotation to produce aconcentrate of the said mineral values.
 15. A process as defined inclaim 14 wherein said effective dispersion of said ore is brought aboutin the presence of a controlled amount, predetermined by experiment ofat least one reagent selected from the group consisting of wettingagents, electrolytes and dispersing agents which are free from ionsdeleterious to flotation.
 16. A process as defined in claim 14 whereinthe mineral values are iron and said effective dispersion of said ore isbrought about in the presence of a controlled amount, predetermined byexperiment, of sodium silicate.
 17. A process as defined in claim 14wherein the mineral values are iron and said effective dispersion ofsaid ore is brought about in the presence of a controlled amount,predetermined by experiment, of sodium sulfate.
 18. A process as definedin claim 14 wherein the mineral values are iron and said effectivedispersion of said ore is brought about in the presence of a controlledamount, predetermined by experiment, of a wetting agent which is freefrom ions deleterious to flotation.
 19. A process as defined in claim 14wherein the activation conditioning stage is carried out at an initialpH, predetermined by experiment, within the range of from about 6.7 toabout 7.2 for a period of time, predetermined by experiment, of fromabout 4 to about 16 minutes.
 20. A process as defined in claim 14wherein the mineral values are iron and the activation conditioningstage is carried out at an initial pH, predetermined by experiment,within the range of from about 6.7 to about 7.2 for a period of time,predetermined by experiment, of from about 4 to about 16 minutes.
 21. Aprocess as defined in claim 14 in which the flocculating conditioningstage is carried out at an initial pH, predetermined by experiment offrom about 5.0 to about 6.5 for a period of time, predetermined byexperiment, of from about 8 minutes to about 16 minutes.
 22. A processas defined in claim 14 in which the mineral values are iron and theflocculation conditioning stage is carried out at an initial pH,predetermined by experiment, of from about 5.0 to about 6.5 for a periodof time, predetermined by experiment, of from about 8 minutes to about16 minutes.
 23. A process as defined in claim 14 wherein the finalconditioning stage is carried out at an initial pH, predetermined byexperiment, within the range of from about 7.2 to about 8.5 with theaddition to the pulp of a controlled amount, predetermined byexperiment, of sodium silicate and for a period of time, predeterminedby experiment of from about 6 to about 21 minutes.
 24. A process asdefined in claim 14 wherein the mineral values are iron and the finalconditioning stage is carried out at an initial pH, predetermined byexperiment, within the range of from about 7.2 to about 8.5 with theaddition to the pulp of a controlled amount, predetermined byexperiment, of sodium silicate and for a period of time, predeterminedby experiment of from about 6 to about 21 minutes.
 25. A process for theflotation of metallic oxides, and metallic oxides with water ofcrystallization in chemical combination occurring in ores as finelydisseminated minerals requiring fine grinding for the liberation of saidminerals from essentially undeslimed pulps thereof, comprising; bringingabout, in a pulp of an ore containing one or more of said minerals in astate of subdivision where the mineral values thereof are substantiallyliberated, effective dispersion of said ore; then in an activationconditioning stage conditioning said effectively dispersed ore in saidpulp with a predetermined amount of a collecting agent for the mineralvalues thereof; then in a flocculation conditioning stage at a pulp pHwithin a range in which the mineral values thereof will flocculate inthe presence of the collecting agent used, conditioning the pulp withthe addition of a dispersing agent until substantial flocculation ofsaid mineral values and effective dispersion of the gangue materialswithout deflocculating the mineral values has occurred; and thensubjecting the thus conditioned pulp to flotation to produce aconcentrate of the said mineral values.
 26. A process as defined inclaim 25 wherein said effective dispersion of said ore is brought aboutin the presence of a controlled amount, predetermined by experiment ofat least one reagent selected from the group consisting of wettingagents, electrolytes and dispersing agents which are free from ionsdeleterious to flotation.
 27. A process as defined in claim 25 whereinthe mineral values are iron and said effective Dispersion of said ore isbrought about in the presence of a controlled amount, predetermined byexperiment, of sodium silicate.
 28. A process as defined in claim 25wherein the mineral values are iron and said effective dispersion ofsaid ore is brought about in the presence of a controlled amount,predetermined by experiment of sodium hydroxide.
 29. A process asdefined in claim 25 where the mineral values are iron and said effectivedispersion of said ore is brought about in the presence of a controlledamount, predetermined by experiment, of sodium sulfate.
 30. A processfor the flotation of metallic oxides and metallic oxides with water ofcrystallization in chemical combination occurring in ores as finelydisseminated minerals requiring fine grinding for the liberation of saidminerals from essentially undeslimed pulps thereof comprising; preparinga pulp of an ore containing at least one mineral selected from the classconsisting of metallic oxides and metallic oxides with water ofcrystallization, which has been finely ground to substantially liberatethe minerals thereof for the process of flotation, in which pulp groundore is effectively dispersed for differential activation; conditioningsaid pulp with collector agent used for flotation of said minerals todifferentially activate said minerals and then adjusting the pH of thepulp to within the optimum range for flotation of said minerals anddepression of the gangue and conditioning said pulp for flotation in afinal stage of conditioning with the addition of dispersing agentwhereby gangue materials in said ore are effectively dispersed while thesaid minerals remain flocculated; and then subjecting the thusconditioned pulp to flotation to produce a concentrate of said minerals.31. A process according to claim 30 in which the pH range within whichsaid final stage of conditioning is carried out is from about 6.7 toabout 8.9 and the predetermined period of time of said final stage ofconditioning is a time predetermined by experiment within the range offrom 3 to 25 minutes.
 32. A process as defined in claim 30 wherein thepulp contains a controlled amount, predetermined by experiment, of anelectrolyte which is free of ions deleterious to flotation.
 33. Aprocess as defined in claim 32 wherein the electrolyte is sodiumsulfate.
 34. A process as defined in claim 30 wherein the pulp containsa controlled amount, predetermined by experiment of a dispersing agent.35. A process as defined in claim 34 wherein the dispersing agent issodium silicate.
 36. A process as defined in claim 30 wherein themineral values are iron.
 37. A process as defined in claim 30 whereinthe mineral values are uranium.
 38. A process as defined in claim 30wherein the ore is an iron ore wherein the mineral values in the ore areselected from the group consisting of hematite, specular hematite,magnetite, martite and goethite.
 39. A process as defined in claim 30wherein the flotation reagent is selected from the group consisting offatty acid, mixtures of fatty acid and petroleum sulfonate and mixturesof fatty acid and petroleum sulfonate and fuel oil wherein the fuel oilis present in amounts not exceeding 5 pounds per ton of solids.
 40. Aprocess as defined in claim 30 wherein the conditioning with collectoragent is in an acid circuit and wherein said conditioning within theoptimum range for flotation of said minerals and depression of thegangue is in an alkali circuit.
 41. A process as defined in claim 40 inwhich the ore is a readily dispersable iron ore wherein the dispersionof the ore for differential activation and the conditioning of the pulpwith a collector agent to differentially activate the minerals iscombined in a single stage.
 42. A process for the flotation of metallicoxides and metallic oxides with water of crystallization comprising; wetgrinding an ore containing one or more of said minerals in the presenceof a quantiTy predetermined by experiment of a dispersing agent and aquantity predetermined by experiment of a collecting agent for saidminerals to produce a pulp of said ore wherein liberated mineral contentthereof is activated; then at a pulp pH within a range in which themineral values thereof will flocculate in the presence of the collectingagent used, in a flocculation stage of conditioning, conditioning thepulp until substantial flocculation of said mineral values has occurred;then at a higher pulp pH within the optimum range of pH for flotation ofthe mineral values thereof, in a final conditioning stage, conditioningthe pulp to bring about effective dispersion of the gangue materialswithout deflocculating the mineral values.
 43. A process as defined inclaim 42 wherein the ore is an iron ore wherein the mineral values inthe ore are selected from the group consisting of hematite, specularhematite, magnetite, martite and goethite.
 44. A process as defined inclaim 42 wherein the flotation reagent is selected from the groupconsisting of fatty acid, mixtures of fatty acid and petroleum sulfonateand mixtures of fatty acid and petroleum sulfonate and fuel oil whereinthe fuel oil is present in amounts not exceeding 5 pounds per ton ofsolid pulp.
 45. A process for the concentration of iron ore occurring asfinely divided minerals of the class consisting of hematite, martite,goethite, magnetite and specular hematite requiring fine grinding forthe liberation of said minerals from essentially undeslimed pulps, whichcomprises subjecting the ore to wet comminution in the presence of apredetermined amount of sodium silicate to produce an effectivelydispersed pulp of said ore; conditioning said ore in the presence of acollecting agent for the iron mineral present to cause flocculation ofsaid mineral; lowering the pH to neutral or slightly lower by theaddition of a suitable acid reagent; further conditioning the pulp inthe presence of a predetermined amount of sodium silicate for apredetermined period of time to maintain the gangue materials dispersedwhile the pH of said pulp rises to within the optimum range forflotation of the said iron mineral to effect and bring aboutflocculation of said iron mineral favorable for flotation; and thensubjecting the thus conditioned pulp to flotation to produce aconcentrate of said iron mineral.
 46. A process for the concentration ofiron ore occurring as finely divided minerals of the class consisting ofhematite, martite, goethite, magnetite and specular hematite requiringfine grinding for the liberation of said minerals from essentiallyundeslimed pulps, which comprises subjecting the ore to wet comminution,adding to said comminuted ore a predetermined amount of sodium silicateto produce an effectively dispersed pulp of said ore; conditioning saidore in the presence of a collecting agent for the iron mineral presentto cause flocculation of said mineral; lowering the pH to neutral orslightly lower by the addition of a suitable acid reagent; furtherconditioning the pulp in the presence of a predetermined amount ofsodium silicate for a predetermined period of time to maintain thegangue materials dispersed while the pH of said pulp rises to within theoptimum range for flotation of the said iron mineral to effect and bringabout flocculation of said iron mineral favorable for flotation; andthen subjecting the thus conditioned pulp to flotation to produce aconcentrate of said iron material.
 47. The improved process of claim 46wherein the collecting agent is a fatty acid collecting agent.
 48. Theimproved process of claim 47 wherein in further conditioning the pulpthe pH thereof is adjusted to within the optimum range for flotation bythe addition of a reagent selected from the group consisting of adispersing agent, a dispersing agent combined with an alkali or analkali dispersing agent.
 49. The improved process of claim 46 whereinthe collecting agent consists of a combinAtion of fatty acid collectingagent and petroleum sulfonate collecting agent.
 50. The improved processof claim 46 wherein the collecting agent is a combination of fatty acidcollecting agent, petroleum sulfonate collecting agent and fuel oil. 51.The improved process of claim 46 wherein the collecting agent consistsof a combination of fatty acid collecting agent and fuel oil.